The present invention relates to a diffusion reflector, and particularly, to a diffusion reflector used for a reflective cylinder of apparatus in which a laser rod is excited by an lamp and the like, and a solid laser device utilizing the former.
Generally, in a solid laser device such as a YAG laser, a glass laser and the like, a flash lamp such as a xenon lamp provided within a reflective cylinder is illuminated and illuminant energy thereof is irradiated on the YAG rod or the glass rod to provide a laser oscillation.
The reflective cylinder is formed into an elliptical sectional shape, and is subjected to metal vapor deposition to form a mirror surface. The laser rod and the exciting lamp are located at the focal point of the ellipse. An exciting light caused by illumination of the exciting lamp is reflected on the inner surface of the reflective cylinder and then incident on the laser rod.
This construction will be specifically described with reference to FIG. 8.
As shown in the figure, a laser rod 12, and lamps 13 and 13 are arranged in parallel within a reflective cylinder 10.
The reflective cylinder 10 has a section formed into a double ellipse, and metal is vapor-deposited on the inner surface thereof.
When the lamps 13 are illuminated, a direct light 13a and a reflective light 13b arrive at the laser rod 12. Since the laser rod 12 and the exciting lamps 13 are arranged at the focal point of the ellipse, all the reflective light 13b are focused on a center portion of the laser rod 12.
However, in such a device as described, the center portion of the laser rod 12 is strongly excited but the outer peripheral portion thereof is not applied with sufficient excitation, resulting in unevenness of distribution of laser gain.
In a case where light from the lamps 13 is smaller than an angle indicated at .theta. in FIG. 8 and radiated in a direction opposite to the laser rod 12, the light is interrupted by the lamps 13 themselves, which poses a problem in that the light cannot arrive at the laser rod 12.
Furthermore, the number of the lamps 13 increases such as a single ellipse in case where there is one lamp 13 and a double ellipse in case of two lamps 13. With this increase, the inner shape of the reflective cylinder 10 becomes complicated. In a case where four lamps 13 are used, as shown in FIG. 7, a complicated shape of a hexaellipse results. The reflective cylinder having such a multi-elliptical construction as described above has a problem in that not only the manufacture is difficult but uniformity of reflective light is further broken to worsen the exciting efficiency.
The present invention has been achieved in view of the background as described above. The present invention has its technical task of obtaining a diffusion reflector which is equality in exciting and high in reflective efficiency in a reflective cylinder which constitutes a solid laser device.